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<h3>SPANA:  Making a Diagram<br>
(run SED or PREDOM)</h3>

<p>A diagram may be made using either of the menu
&#147;Run / <nobr>make a Diagram&#148;</nobr>
or &#147;File / <nobr>Data file</nobr> / Open <nobr>(make a diagram)&#148;</nobr>
in the main SPANA window. A new window appears where you can enter
all parameters needed to make a diagram with
<nobr><a href="SP_0_Main.htm">SED/PREDOM</a>:</nobr></p>

<p><center>
<img src="images/Select_Diagr_Type.gif" alt="Select_Diagr_Type" title="Select_Diagr_Type" height="376" width="500">

</center></p>

<p><b>Data File Name</b>: It is possible to change the input file by
clicking this field.</p>

<p><b>Diagram Name</b>: Enter a name for the plot file.</p>

<p><a name="Diagram"></a>
<b>Diagram:</b></p>
<ol style="roman">
<li>Select first a diagram type from the pull-down menu</li>
<li>Change the component(s) in the <nobr><i>X-</i></nobr> and <nobr><i>Y-</i>axis.</nobr>
    Change the axes min/max values by clicking on them and entering new values.</li>
<li>For redox systems (containing <nobr>&#147;e&#8722;&#148;),</nobr>
    decide to choose <a href="1_Eh_pe.htm">pe or redox potential</a> (Eh) by
    clicking the corresponding check-box.</li>
<li><b>Title:</b> If you have selected advanced program level (in the menu Preferences / General options)
		you may enter a title for the diagram.</li>
</ol>

<p><b>Concentrations:</b>  Change the concentration for each component by
clicking on their line within the list-box.</p>

<p><a name="Parameters"></a>
<b>Parameters:</b>  The default values for the parameters can be set by
clicking on the &#147;Save as defaults&#148; button.
<i>Note</i> that some of the parameters listed below might not appear in the window,
depending on the type of diagram selected and program level
(normal or advanced in the menu Preferences / General options).</p>
<ul>
<li><b>Ionic strength:</b> This is only meaningful for <i>aqueous systems.</i>
  If a value is given, the programs assume that the equilibrium constants in the
  input file are valid at infinite dilution (<b><i>I</i></b> = 0)
  and the effects of <a href="SP_Ionic_Strength.htm">ionic strength</a>
  will be calculated.<sub>&nbsp;</sub><br>

  If <b><i>I </i></b>= &#8722;1 is given, then the ionic strength will be
  calculated iteratively assuming electroneutrality for the system:
  sodium or chloride ions will be added to keep each calculation point
  electrically neutral before calculating the ionic strength of the aqueous
  solutions.<br>
  See <a href="SP_Ionic_Strength.htm#Models">activity coefficient models</a>.
	</li>

<li><a name="Temperature"></a>
  <b>Temperature:</b> This is only meaningful for aqueous systems, and in
  most cases it is not needed. The temperature is <i>only</i> used to calculate
	<ul><li>ionic strength effects
	<li>to convert <a href="1_Eh_pe.htm">pe</a>
  to redox potential (if the redox potential must be calculated
  from  <a href="1_Eh_pe.htm">pe</a>)</li></ul></li>

<li><b>Number of calculation steps:</b> The number of steps in each axis
  (default is 50). Because the programs use a point-by-point plotting technique,
  increasing this number will increase the resolution of the diagrams. However, this
  will require longer execution times!</li>

<li><a name="Table_Output"></a>
  <b>Output a table with results (SED):</b> output files can be generated by SED with
the curve-values in the plots. These are plain text files that will get names
like SED000, SED001, etc. You can use these files to insert the tabulated
values into a spread-sheet (such as Excel), or you can plot the data with
some other plotting program.
See menu: <a href="S_Menu_Prefs.htm#Table">calculation options</a>.</li>

<li><a name="Only_Aqu"></a>
  <b>Show only aqueous species (PREDOM):</b> This will create a predominance
  area diagram <b>not</b> showing any solid phases that might predominate in
  parts of the diagram. In this way the underlying aqueous speciation may be
  visualised.</li>

<li><b>Allow reversed concentration ranges:</b> Normally the minimum and maximum
  concentration limits in the axes are arranged so that minimum values are closer
  to the origo. If for any rason you need to change that, click on this check box
  and change the concentration limits. <a href="S_Diagr_Rev_Conc.htm">Example of
  a diagram with reverse concentrations</a>.
  </li>

<li><b>For e&#8722;: use Eh</b> check the box to display the <a href="1_Eh_pe.htm">redox potential</a>
	instead of <a href="1_Eh_pe.htm">pe</a> as variable in the axes or in the caption.  
  </li>
</ul>


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